1. Field of the Invention
The present invention relates to a variable capacity rotary compressor, and more particularly, to a variable capacity rotary compressor capable of preventing collision due to slipping of eccentric bushes.
2. Description of the Related Art
Generally, a variable capacity rotary compressor has an eccentric unit that allows selective eccentric rotation of a roller disposed in a respective one of two compression chambers depending on a rotational direction of a rotary shaft, thereby selectively performing a compression operation. This technology for a variable capacity rotary compressor that is capable of varying refrigerant compression capacity, is disclosed in Korean Patent Application No. 10-2002-0061462 filed by the assignee of the present invention. Such an eccentric unit includes two eccentric cams formed on an outer circumference of the rotary shaft while corresponding to the compression chambers, respectively, two eccentric bushes rotatably coupled around the two eccentric cams to bear rollers against their outer circumferences, respectively, and a latch pin for latching one of the two eccentric bushes (also referred to as bushings) to its eccentric position and the other one to its non-eccentric position upon rotation of the rotary shaft. The eccentric unit operates to allow the compression operation to be carried out in only one of the two compression chambers with different capacities, thereby realizing variable capacity operation through simple change of the rotational direction of the rotary shaft.
Another kind of a variable capacity rotary compressor that is capable of preventing slip of the eccentric bushes during the compression operation as stated above is disclosed in Korean Patent Application No. 10-2003-0044459, filed by the assignee of the present invention. The disclosed compressor has a restraint unit for restraining the eccentric bushes upon rotation of the rotary shaft. Such a restraint unit includes a restraint member adapted to protrude outward from the rotary shaft upon receiving a centrifugal force caused by rotation of the rotary shaft for restraining the eccentric bushes, an inner supporting pin mounted in the rotary shaft to limit a forward/backward movement range of the restraint member, and a return spring fitted on the outer circumference of the inner supporting pin and adapted to return the restraint member inward toward the center of the rotary shaft when the rotary shaft is not rotated so as to remove restriction of the eccentric bushes.
The compressor as stated above restrains the eccentric bushes as the restraint member protrudes outward from the rotary shaft upon receiving the centrifugal force caused by rotation of the rotary shaft, thereby preventing slip of the eccentric bushes and hence preventing generation of noise due to collision between the eccentric bushes and the latch pin.